Independent evolution of betulin biosynthesis in Inonotus obliquus

Area of Science:

• Mycology
• Genomics
• Biochemistry

Background:

• Chaga mushroom (Inonotus obliquus) causes white rot in birch species.
• Understanding its genome is key to its unique biochemical properties.

Purpose of the Study:

• To assemble the Inonotus obliquus genome.
• To investigate the role of genome duplication in its metabolic diversity.

Main Methods:

• PacBio sequencing for genome assembly.
• Comparative genomics to identify lineage-specific events.
• Metabolomic fingerprinting for chemical analysis.

Main Results:

• A 50.7 Mbp genome was assembled.
• A whole genome duplication event was identified ~1.3 million years ago.
• Increased complexity in terpene biosynthesis was observed, linked to cytochrome P450 expansion.

Conclusions:

• Genome duplication significantly contributed to Inonotus obliquus's biochemical diversity.
• This metabolic evolution may be a result of co-evolution with Betula species.
• The findings provide insights into fungal adaptation and secondary metabolism.